Method of forming wood wool panels



Oct. 13, 1953 H. w. COLLINS F' FORMING WOOD WOOL PANELS METHOD O 2 Sheets-Sheet l Filed Nov. l

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llllllllllltl Oct. 13, 1953 H. w. COLLINS METHOD OF' FORMING WOOD WOOL PANELS 2 Sheets-Sheet 2 Filed Nov. l, 1951 lllllll I6 ZB 30 A TTRNE YS.

Patented Oct. 13, 1953 2 UNITEDu STATES PATENT OFFICE MemonorronnnronwooL-Mms HowardA W. Collins, Newark, Ohio,` assignmto Tectuin Corporatinm Newark, (16h10,r a. corporation of Ohio Application N ovemher 1, 1951, Serl'al. Noi/41551 8 Claims. (Cl. 154-101)` in a continuous process. This application: is.` a is leaving the press. continuation-in-part of my applicatiom Serial Itfis a further object: of my invention topra- Nol` 7905914; led December. 110, 1947 now abanvidela methodot forming woodwool panels wheredoned; and entitled,I Method of Forming Wood in the process is continuousl and wherein rotat- Wool Panels. ingl machinery may beused aswellasrubber belts In thepreblem oi toi-ming` a Wood-.Woolmagnefor conveying purposes,A4 since the temperature to si-u-m cement panell a continuous process,V cer- 10 which the equipment andy belts are subjected` is tain; very denite problems. present themselves reasonably below a temperature which would which are not present when the process is not vaporizeor injureranylubricating. means: or injure continuous.. therubber or fabric conveyor belts.

Magnesium cement as preferably used in my A further object ofmy invention is-to, provide a.

processconsistsv of ay Water-borne mixture. of l method of forming wood wool panels by a conmagnesiumy oxideandmasnesium sulphate The nuous process which is commercially practical magnesium oxide. andfmagnesiumsulphate is.com.- relatively inexpensive to maintain, includesv simbined just. before itisfsprayed, on. the. wood wool. ple moving, parts and moving machinery and While it. immediately commences. to react, chemihence is relatively easyto-adg-ustandV repair when cally, the time it sets is well over an. houn Inra necessary..

vision be made for greatly speeding up the setting on and arrangement of steps of which I shall time of the magnesium cement. now describe an exemplary embodiment.w Ref- In my process, after. the cement has been added erence is now made tothe drawmgs which form to, the wood wool which. is matted on. a belt cona part thereof andinwhichc veyor, it` movedl by the conveyor and at some Figures l and la ar vside elevational diagrams stage before the completion ofthe panel., the conin: sectionof the apparatus. Figure la being a veyor carries the. mat between` the plates or: rolls continuation of Figure 1.

of, a heatedi press which forms the mat into a Figure 2 avcletailed4 section on a larger scale panel of the desired thickness Thus, itis necestaken on the section line 2-`2 of Figure 1 sary that the cement` set sufiiclently to maintain Figure 3 1s a graph showing the diierent temthe thickness of the formedpanel before it leaves pepatures at durerent'times throughout my novel the press, but not before the press has acted upprocess on the mat Hence, 1t isaJ problem when forming While wood wool panels have previously Ibeen mdb a moving" .belt'mfpe @meyer of the usual temperatureisuch as-500P'Ff At such heats; it is, 50 slum. cement consists substantially of a mixture o1' course, impossible to` use rotating' machinery, of 35%l magnesium'f, sulphate dissolved in water to since any lubricant` wouldbe dispersed or boiled whichV has beenV added %,f of magnesium; ox-ide. away andanyI rubber oriabric-material; such as These percentages are not. critical; but merely exa conveyorh be1t, would be quickly disintegrated. emplary. sincethe qualityot themagnesium oxide It. is' an` objectL of my inventionI to,l provide a 55 may vary substantially andthe: amount be varied 'sist in matting the wood wool. with the preheating oven is a chamber to which in accordance with its previously found chemical activity.

Just as soon as the magnesium oxide has been mixed with magnesium sulphate solution, the resulting cement commences to set. However, the setting at normal temperatures takes well over an hour. The chemical reaction between magnesium oxide and magnesium sulphate is exothermic and in order to take advantage of this and to greatly decrease the setting time of the cement, I have provided at the first station along the moving loaded conveyor belt a preheating oven.

This preheating oven is a very important feature of my method, since the temperature to which the preheating oven is maintained determines the time within which the magnesium cement will set. The preheating oven consists of which the wood wool matting is carried and inrvcludes blowers which blow heated, water-saturated air down through the matting and preferably through the conveyor belt which is foraininated to permit the passage of this air and as- Communicating is run a source of steam through a valve which is thermostatically controlled so as to admit ber is raised to a predetermined temperature.

The temperature of the vapor or water saturated air in this chamber usually ranges from 110 F. to 140 F. The vapor in the chamber at its predetermined temperature flows into the prem heating oven and thence through the mat upon the conveyor.

The limits of 110 F. to 140 F. in the oven will result in the magnesium cement setting from about the maximum of 101/2 minutes to a minimum of 4 minutes. The ratio oi the temperature to the time of setting is dependent upon the chemical activity7 of the magnesium oxide used in the cement and hence this activity is predetermined, and a graph such as that shown in Figure 4 is prepared for the given batch of magnesium oxide.

Since the heating vapor used in the preheating oven is water-saturated air of a predetermined temperature, the vapor or air entering the preheating oven is completely saturated with a relative humidity of 100%.

At the next station along the belt conveyor, I provide for the actual press which forces the matted material together and forms the panels at their predetermined thickness. The press preferably used by me consists ci two rubber conveyor belts backed up by a series of transverse platens which contact each other to form a plate when in the horizontal or pressing position. Hence, the press while acting as two plates press on each side of the matted material, also acts as a conveyor Jfor moving material through the press.

As stated above, it is important that the magnesium cement, when the matting reaches the press, be in a condition where it has not quite set since the press itself crushes and diminishes the thickness oi the mat and if the cement were set, it would be broken by the crushing action.

On the other hand, after the material has been compacted and pressed to predetermined thickness, the cement should be set at least suiciently to maintain this thickness.

I preferably keep the temperature of the press about 190 F., but this temperature is not sui- L( cient to speed up the setting action of the cement sufficiently for a continuous process such as mine. As an example, with the temperature of the press at 190 F. and using a mat thickness of wood wool that results in a three inch panel, it would still take 45 minutes from the time the cement is applied to the mat for it to set suiriciently for my purpose. This, of course, is entirely too long for a continuous process such as mine.

In order to provide for a continuous process with cement of this type, I predetermine the distance between the point on the moving conveyor where the cement is applied to the material and the outlet end or my press. Since the material is moved to and through the press at a uniform rate of speed, the distance between these two Thus, by using a chart similar to that shown in Figure 4, I can determine what the temperature shall be in the preheating oven to insure the setting of the cement at the proper place in the press. Of course, for mats of diierent thicknesses, the speed of the conveyor belt is varied but the rate is always kept uniform.

As an example, if in accordance with the speed of my conveyor belt it will take 81/4 minutes for the material to run from the point where the cement is applied to the exhaust end of the press; I will look at my graph similar to Figure 4 and note that a temperature of 120 F. is correct for the preheating oven.

It will be noted from the above that by predetermining the heat in the preheating oven,

" it will add to the exothermic heat created by the chemical action of the cement so as to speed up the setting of the magnesium cement and thus make it possible to form wood wool panels in a relatively rapid continuous process. By using water-saturated vapor in the preheating oven, I add very little moisture to the material and any excess, of course, is removed in the iinal drying ovens.

Referring to the drawings, Figures l and la show my apparatus schematically. A moving conveyor belt I is provided which travels at a predetermined constant speed depending upon V lthe thickness of the wood wool mat 2. The loose wood wool 3 is placed upon the conveyor belt i in a uniform manner and is saturated with magnesium cement consisting of a mixture of waterborne magnesium sulphate and magnesium oxide by the sprays The water-borne cement may be distributed over the mat after it has been positioned on the conveyor belt I; but in Figure 1, I have merely shown the nozzles 4 in the chute leading to the belt. However, the method of saturating the mat is not critical to my process.

As the conveyor belt i moves to the right in Figure l, the mat. 2 comes within the preheating oven 5. There is a chamber E connected to the preheating oven 5, and a steam valve controlled by a thermostat regulates the steam entering and mixing with the air in the chamber E until a -predetermined temperature is reached at which the thermostat 8 shuts 01T the steam valve l. This temperature is predetermined by use of a chart similar to that shown in Figure 4.

While the mat 2 is in the preheating oven 5, the hot vapor oi the oven combined with the exo thermic heat of the chemical reaction within the magnesium cement raises the temperature so that the setting time of the magnesium cement is 75 greatly decreased and controlled so it will set up sufficiently, while the mat is within the press `9 which it is dried by forced hot air as it passs at the next station along the line. through a series of drying ovens. After the mat After the mat 2 leaves the preheating oven 5, leaves these drying ovens, it is cut to size and is it enters the press 9. rl'his vpress is preferably ready for shipping.

composed of opposed `rubber conveyor belts l 5 The detailed procedure necessary to accomwhich are backed yup by metal platens Il which plish this method or practice is substantially as form a dat surface when in the horizontal posifollows:

tion, as shown in Figure 1 of the drawing As First of all, the batch of magnesium oinde to belts lof the press crush the mat to its prefrom these results `a graph such as that shown in determined nal thickness .and hence it is :im- Figure 4 1s prepared After the graph has been portant that the magnesium cement be relatively made, the temperature of the preheating oven plastic and not sufficiently set to result inabreakis predetermined by use of the graph and ing up or disintegration .of the cement during the thermostatic control valve is set accordingly.

this crushing action. I preferably `maintain the After setting ofthe thermostatic valve 8, there is temperature of the press 9 at approximately Ano other adjustment to be made, assuming that 190 F.

As the mat `2 moves through the press, the ness and the speed of the conveyorl belt adjusted magnesium Cement sets suiicientiy to `maintain in accordance with the thickness desired. the `thickness formed by the press, `so when the As the mat enters the preheating oven, the mat leaves the press as at 2 it `will not swell or saturated vapor is forced downwardly through the expand, but will remain Vthe desired .predetermat so that the heat of the vapor, together with mined thickness. the `exothermic heat generated by the chemical In order to insure the `complete setting of the action, speeds up the setting of the cement. The

2 just beyond` the exit of the .press 9.` This the temperature of the Vapor Within the oven is Ychamber l21`s maintained `at the same temperarelatively negligible and, of course, all excess `turcas the press, that is about 199 F. and is ineremoisture is removed by the drying ovens at the ly for the purpose of insuring the complete set- .30 end of the run.

ting of the magnesium `cement and `eliminating It should be particularly noted that throughout the `necessity of making the relatively expensive e apparatus, no part or portion has been elepress 9 sufficiently long for this purpose. After vated above 220 F. and hence rotating equipthe formed mat leaves the chamber l2, it enters ment where lubrication is needed and rubber a series of drying ovens I3 wherein heated airis 35 and liber belts which deteriorate at high temblewn through the mat, thus removing excess perature maybe used.

moisture. While in AFigure la, I have merely The charts `and drawings I have shown are not this graph is merely "exemplary and depicts the 15 cordance with the thickness of the mat and -belt conveyor moving at the rate of six feet a the desired final pand It is to `be understood thatmodication ma be Depending upon the chemical activity of the inagmade in my invention Wit y nesium Oxide the temperatur@ 0f the @rehearing the spirit thereof, and i do Vhet intend to limit upon the speed of the belt conveyor. which follow Figurei shows an exemplary :graph Where the Having thus described my invention what i preheatlng temperature is plotted against time" claim as new and desire to secure by Letters This graph is used in determining the preheating Patent is:

temperature of this oven depending Upon the 1. The method of magnesium oxide and in accorda-nce with an heated air being such that the cement will set sulciently to hold the layer against expansion tinuous process. As can be seen from the graph Whlle the layer 1s between the compressing sur' from its point of application to the end of the am; magnes-1um-cement-rapdly and Continuously,

prevent the expanding of the mat is less than impregnated with Water borne magnesium oxide twenty-six minutes. As stated above, the mat and magnesium Salts 0f the group 0f Sulphate then passes through a heated chamber which asand chloridey Continuously passing the layer sures the complete setting of the cement after through a current of heated air and then passing the layer between continuously moving compressing surfaces, the temperature of the heated air being such that it will supplement the exothermic heat developed by the reaction oi the magnesium cement to a point where the cement will not set before the layer passes between the compressing surfaces but will set sufficiently to hold the layer against expansion before it passes from between the compressing surfaces.

3. The method of forming a panel of wood wool and magnesium cement rapidly and continuously, which consists in forming a layer of wood wool impregna-ted with water borne magnesium oxide and magnesium salts of the group of sulphate and chloride, continuously passing the layer through a current of heated air and then passing the layer between continuously moving compressing surfaces, the temperature of the heated air being such that it will supplement the exothermic heat developed by the reaction of the magnesium. cement to a point where the cement will not set before the layer passes between the compressing surfaces but will set sufliciently to hold the layer against expansion before it passes from between the compressing surfaces, and then main-taining the temperature of the layer until the cement has completely set and iinally drying the layer so as to remove excess moisture.

4. 1n the method of rapidly and continuously forming a. cement bonded wood wool panel wherein a layer of wood wool impregnated with a mixture of water borne magnesium oxide and magnesium sulphate is continuously moved between compressing surfaces, that step which consists in passing the layer through a draft of heated vapor prior to its movement between the compressing surfaces wherein the temperature of the heated vapor 1s predetermined to supplement the exothermic heat of the cement to a degree where it will set to an extent preventing expansion of the layer after the layer has been released from between the compressing surfaces.

5. That step in `the method of rapidly and continuously forming a magnesium cement bonded mat of wood wool, which consists in forming a layer of the required thickness of wood wool mixed with water-borne magnesium oxide and magnesium salts of the group of sulphate and chloride, and immediately passing the layer while held on a foraminous traveling support, through a draft of air heated to a temperature to supplement the exothermic heat which the magnesium salt and oxide reaction would develop of itselfy and controlling the moisture in the air so that it neither wets nor dries the layer to any substantial extent during said passage, whereby a rapid reaction takes place suitable for a continuous process.

6. That step in the method of rapidly and continuously forming a magnesium cement bonded mat of wood wool, which consists in forming a layer of the required thickness oi wood wool mixed with water-borne magnesium salts of the group of sulphate and chloride, and immediately passing the layer while held on a foraminous traveling support, through a draft of air heated to a temperature between F. and 140 F. and controlling the moisture in the air by saturating the same with moisture so that it does not dry the layer during said passage, whereby a rapid reaction takes place suitable for a continuous process.

'7. The method of forming a mat of wood wool and magnesium cement rapidly and continuously to a condition of stiffness suitable for handling without deterioration, which consists in forming the layer of wood wool and water-borne magnesium oxide and magnesium salt of the group of sulphate and chloride, continuously passing the layer through a current of heated watersaturated air so las not to dry the layer, passing the layer between continuously moving compressing surfaces to condense it to a .predetermined density while maintaining heat conditions, maintaining the temperature of the layer until all chemical reaction has ceased, and then drying the mat by passing it through currents of dry air, the temperature of the layer at no stage throughout the process being greater than 220 F.

8. The method of forming a panel of wood wool and cement rapidly and continuously which consists in forming a layer of wood wool impregnated with a water-borne dry powder ceinentitious material settable upon hydration by an exothermic reaction, continuously passing the layer through a current of heated air and then passing ythe layer between continuously moving compressing surfaces, the temperature of the heated air being such that the cement will set 'sufiiciently to hold the layer against expansion while the layer is between the compressing surfaces.

HOWARD W. COLLINS.

References Cited in the file of this patent UNITED STATES PATENTS n nn,... 

1. THE METHOD OF FORMING A PANEL OF WOOD WOOL AND MAGNESIUM CEMENT RAPIDLY AND CONTINUOUSLY, WHICH CONSISTS OF FORMING A LAYER OF WOOD WOOL IMPREGNATED WITH WATER BORNE MAGNESIUM OXIDE AND MAGNESIUM SALTS OF THE GROUP OF SULPHATE AND CHLORIDE, CONTINUOUSLY PASSING THE LAYER THROUGH A CURRENT OF HEATED AIR AND THEN PASSING THE LAYER BETWEEN CONTINUOUSLY MOVING COMPRESSING SURFACES, THE TEMPERATURE OF THE HEATED AIR BEING SUCH THAT THE CEMENT WILL SET SUFFICIENTLY TO HOLD THE LAYER AGAINST EXPANSION WHILE THE LAYER IS BETWEEN THE COMPRESSING SURFACES. 